Riley, RD, Ahmed, I, Ensor, J, Takwoingi, Y, Kirkham, A, Morris, RK, Noordzij, JP and Deeks, JJ (2015) Meta-analysis of test accuracy studies: an exploratory method for investigating the impact of missing thresholds. Systematic Reviews, 4. 12 -?. ISSN 2046-4053

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BACKGROUND: Primary studies examining the accuracy of a continuous test evaluate its sensitivity and specificity at one or more thresholds. Meta-analysts then usually perform a separate meta-analysis for each threshold. However, the number of studies available for each threshold is often very different, as primary studies are inconsistent in the thresholds reported. Furthermore, of concern is selective reporting bias, because primary studies may be less likely to report a threshold when it gives low sensitivity and/or specificity estimates. This may lead to biased meta-analysis results. We developed an exploratory method to examine the potential impact of missing thresholds on conclusions from a test accuracy meta-analysis. METHODS: Our method identifies studies that contain missing thresholds bounded between a pair of higher and lower thresholds for which results are available. The bounded missing threshold results (two-by-two tables) are then imputed, by assuming a linear relationship between threshold value and each of logit-sensitivity and logit-specificity. The imputed results are then added to the meta-analysis, to ascertain if original conclusions are robust. The method is evaluated through simulation, and application made to 13 studies evaluating protein:creatinine ratio (PCR) for detecting proteinuria in pregnancy with 23 different thresholds, ranging from one to seven per study. RESULTS: The simulation shows the imputation method leads to meta-analysis estimates with smaller mean-square error. In the PCR application, it provides 50 additional results for meta-analysis and their inclusion produces lower test accuracy results than originally identified. For example, at a PCR threshold of 0.16, the summary specificity is 0.80 when using the original data, but 0.66 when also including the imputed data. At a PCR threshold of 0.25, the summary sensitivity is reduced from 0.95 to 0.85 when additionally including the imputed data. CONCLUSIONS: The imputation method is a practical tool for researchers (often non-statisticians) to explore the potential impact of missing threshold results on their meta-analysis conclusions. Software is available to implement the method. In the PCR example, it revealed threshold results are vulnerable to the missing data, and so stimulates the need for advanced statistical models or, preferably, individual patient data from primary studies.

Item Type: Article
Additional Information: This is the final published version of the article (version of record). It first appeared online via Springer Nature at - please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: Meta-analysis, Diagnostic test, Multiple thresholds, Imputation, Missing data, Sensitivity analysis
Subjects: R Medicine > R Medicine (General) > R735 Medical education. Medical schools. Research
Divisions: Faculty of Medicine and Health Sciences > Primary Care Health Sciences
Related URLs:
Depositing User: Symplectic
Date Deposited: 28 Apr 2017 15:11
Last Modified: 13 Aug 2018 10:28

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